* [configs] Remove requires systemd-networkd dep from smfd service
The smf no longer has (never had?) a dependency on systemd-networkd,
and can start and remain operational without systemd-networkd
specifically running.
* [configs] Relax upf dependency on systemd-networkd
The upf relies on systemd-networkd to create the ogstun interface, but
does not communicate with it at runtime. It currently has a "Requires"
dependency specified, which means that the upf will be stopped if
systemd-networkd is ever stopped. Since the upf doesn't actually care
if systemd-networkd is later stopped after ogstun is created, it can
use the weaker "Wants" dependency type, which allows it to keep
running even if systemd-networkd were to be stopped.
Regardless, since it does rely on systemd-networkd specifically to
create the ogstun interface, it should sequence itself "After"
systemd-networkd has been started.
Since the true dependency is ogstun, not systemd-networkd, a cleaner
approach would depend on the specific tunnel device being
available. Systemd exposes this information via device units, but I'm
not sure if they are always consistently named across platforms.